Reading E-books before bedtime and their potential negative impacts on sleep

Researchers at Brigham and Women’s Hospital (BWH) compared the biological effects of reading a light-emitting (LE) electronic device, such as an E-book, to a printed book.

The study found that the body’s natural circadian rhythms were disrupted by short-wavelength enriched light, also known as blue light, emitted by these electronic devices.

In the study, researchers observed that participants that read E-books before bedtime took longer to fall asleep and were less sleepy in the evenings. The reason for this is because the blue light of the electronic devices reduces individuals’ secretion of melatonin, a hormone responsible for inducing sleepiness.

Additionally, individuals that used LE electronic devices and E-books before bedtime spend less time in REM sleep and have reduced duration and quality of sleep. Such individuals were found to be sleepier and less alert the next morning after having eight hours of sleep.

Electronic devices that BWH researchers used in the study included iPads, other E-readers, laptops, cell phones and LED monitors, all devices that emit blue light.

The blue light emitted from these electronic devices can significantly affect the body’s natural sleep-wake pattern and accordingly, plays a role in the sleep deficiency of individuals who use such devices in the hours before bedtime.

Researchers also found that E-book readers had delayed circadian rhythms of more than one hour, compared to printed book readers.

Public awareness of the impacts associated with the use of blue light-emitting electronic devices before bedtime are important as their use is becoming more common amongst individuals for reading, communication and entertainment, especially in children and adolescents.

The resulting suppression of melatonin levels due to the use of LE electronic devices before bedtime does not only concern sleep, but, based on evidence from a different study, is also linked to an increased risk of breast cancer, colorectal cancer and prostate cancer.

Accordingly, researchers stress the importance of the findings of this study as they are related to other serious health conditions.

For further reading about this topic, you can find the article at the following link:

The research study could be found at this link:

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